ABSTRACT
Noninvasive prenatal testing accurately detects trisomy for chromosomes 13, 21, and 18, but has a significantly lower positive predictive value for monosomy X. Discordant monosomy X results are often assumed to be due to maternal mosaicism, usually without maternal follow-up. We describe a case of monosomy X-positive noninvasive prenatal testing that was discordant with the 46,XX results from amniocentesis and postnatal testing. This monosomy X pregnancy doubled the single X chromosome, leading to 45,X/46,XX mosaicism in the placenta and uniparental isodisomy X in the amniotic fluid. Thus, at least some discordant monosomy X results are due to true mosaicism in the pregnancy, which has important implications for clinical outcome and patient counseling.
Subject(s)
Fetal Growth Retardation/genetics , Prenatal Diagnosis , Turner Syndrome/genetics , Uniparental Disomy/genetics , Amniocentesis , Female , Fetal Growth Retardation/diagnosis , Genetic Testing , Humans , Infant, Newborn , Karyotyping , Monosomy/genetics , Placenta/physiopathology , Predictive Value of Tests , Pregnancy , Turner Syndrome/complications , Young AdultABSTRACT
Cell polarity is crucial for the generation of cell diversity. Recent evidence suggests that the actin cytoskeleton plays a key role in establishment of embryonic polarity, yet the mechanisms that maintain polarity cues in particular membrane domains during development remain unclear. Dynamin, a large GTPase, functions in both endocytosis and actin dynamics. Here, the Caenorhabditis elegans dynamin ortholog, DYN-1, maintains anterior polarity cues. DYN-1-GFP foci are enriched in the anterior cortex in a manner dependent on the anterior polarity proteins, PAR-6 and PKC-3. Membrane internalization and actin comet formation are enriched in the anterior, and are dependent on DYN-1. PAR-6-labeled puncta are also internalized from cortical accumulations of DYN-1-GFP. Our results demonstrate a mechanism for the spatial and temporal regulation of endocytosis in the anterior of the embryo, contributing to the precise localization and maintenance of polarity factors within a dynamic plasma membrane.
Subject(s)
Caenorhabditis elegans Proteins/metabolism , Caenorhabditis elegans/cytology , Caenorhabditis elegans/embryology , Cell Polarity , Dynamins/metabolism , Embryo, Nonmammalian/cytology , Actins/metabolism , Animals , Biomarkers/metabolism , Cell Membrane/metabolism , Embryo, Nonmammalian/enzymology , Endocytosis , Gene Deletion , Protein Transport , Spindle Apparatus/metabolismABSTRACT
Animal and plant cytokineses appear morphologically distinct. Recent studies, however, have revealed that these cellular processes have many things in common, including the requirement of co-ordinated membrane trafficking and cytoskeletal dynamics. At the intersection of these two processes are the members of the dynamin family of ubiquitous eukaryotic GTPases. In this review, we highlight the conserved contribution of classical dynamin and dynamin-related proteins during cytokinesis in both animal and plant systems.
